This invention relates generally to the remote measurement of fluid temperature and particularly to a temperature measurement system which operates by analysis of backscattered Raman radiation.
Water, having high heat capacity and being the most abundant compound on the surface of the earth, has been used extensively as a coolant and heat exchange fluid in various kinds of experimental and practical equipment. For example, in nuclear reactors it is desirable to operate at the highest practicable temperature owing to the fact that at higher temperatures the efficiency for conversion into useful power is greater. Since an increase in temperature decreases the density of water and therefore the cooling efficiency, pressure is usually applied to the cooling system. Under extreme conditions of high pressure and high temperature, the temperature of water is normally measured by thermocouples or, in the case of a nuclear reactor, a boron thermopile. Inserting a thermocouple into the point of interest has the effect of interfering with the flow pattern of the water and, correspondingly, with the local temperature. Another limitation in the nuclear reactor situation is that the temperature is only indirectly measured by the density of neutron flux. Both thermocouples and thermopiles are permanently engineered into the reactor system and any replacement or redesigning is not easily undertaken especially in a high pressure system.